1. Field of the Invention
This invention relates to a yarn unevenness information analyzing apparatus for detecting a yarn unevenness in a spinning machine including a large number of spinning units.
2. Prior Art
One of spinning machines which include a large number of spinning units is a pneumatic spinning machine and is shown, for example, in FIGS. 3 and 4 of the official gazette of Japanese Patent Laid-Open Application No. Heisei 2-221427. The pneumatic spinning machine is described with reference to FIGS. 9 and 10. FIG. 9 is a view showing essential part of each spinning unit. Referring to FIG. 9, reference numeral 24 denotes a back roller, 25 a middle roller, and 26 a front roller, and an apron 27 in the form of an endless rubber belt extends around the middle roller 25. Each of the rollers 24, 25 and 26 includes a top roller at an upper position and a bottom roller at a lower position and performs drafting of a sliver S. Reference numeral 28 denotes an air jet nozzle, which twists the sliver S coming out from the front roller 26 to produce a spinning yarn Y. Reference numeral 29 denotes a delivery roller for drawing out the yarn from the spinning nozzle 28, and 11 a yarn unevenness detector, that is, a slub catcher, of the photoelectric conversion type for detecting a variation of the thickness of the yarn Y to output a yarn unevenness signal. It is to be noted that a yarn speed is detected by means of a sensor 36 located in the proximity of the lower front roller 26a. The yarn speed is controlled by a master computer not shown for the entire spinning machine.
FIG. 10 is a detailed view of the yarn unevenness detector. Referring to FIG. 10, the yarn unevenness detector or slub catcher 11 is a detector 11 of a high sensitivity and a high responsibility of the type which includes a light emitting diode 30 and a phototransistor 31 and detects an amount of light emitted from the light emitting diode 30 by means of the phototransistor 31 and outputs the amount of light thus detected as an electric displacement between terminals. When a slub is encountered and a very large displacement of the amount of electricity is detected, a cutting apparatus 32 operates in response to the signal to cut the yarn Y at the location. The electric signal from the yarn unevenness detector or slub catcher 11 is utilized as a yarn unevenness analysis signal.
The electric signal from the yarn unevenness detector is conventionally analyzed generally in the following manner. In particular, the electric signal is converted into a digital signal and then processed by Fourier transform or integration processing for a fixed section. The signal after such Fourier transform is analyzed by spectrum analysis, and it is specified from a frequency of a peak portion of the signal by which one of rollers of the spinning unit a periodic unevenness is caused. The result of the spectrum analysis is used principally as maintenance information of the spinning machine so that maintenance of the spinning machine is performed. Meanwhile, the signal processed by integration processing represents a total amount of non-periodic yarn unevennesses and is used as quality information of the yarn.
By the way, while the analysis time for periodic yarn unevennesses described above is as short as one minute or so since the frequency of occurrence of the periodic yarn unevennesses is equal to the period of rotation of a roller or the like, the analysis time for non-periodic yarn unevennesses is as long as 4 to 10 minutes or so since the frequency of occurrence of such non-periodic yarn unevennesses is low. In the spinning machine described above, signals from different spinning units are successively changed over by means of a multiplexer or the like to analyze them by means of a single analyzing apparatus. Accordingly, there is a problem in that the interval of analyses of periodic yarn unevennesses for different spinning units, which are required to be performed rapidly in order that results of them may be used for maintenance, is long.